Conventional materials have been used traditionally for exterior protective surfaces on residential and industrial structures. Brick has been a leading siding material for many years. Stucco has found significant use in new construction in the southern and western regions of the United States. Wood siding has also been a popular choice for many years. Traditional wood siding in a clapboard or shake is characterized by a tapered shape from a rather thick base portion to a rather thin upper edge. This design permits the siding to be nailed to the studs or other framing components of the house in overlapping relationship, in which the lower edge of each course overlaps the upper edge of the next lower course so as to shed rain.
Currently, aluminum, hardboard, Masonite.TM., plywood and vinyl have dominated the siding market because of their lower cost and maintenance as compared with brick, stucco or wood. These materials have been fabricated to simulate the shape and texture of the classic clapboards, wood shakes and shingles that consumers prefer. The shapes and textures of the classic exterior surface materials produce attractive patterns of highlights and shadow lines on walls as the sun shifts in position during daylight.
Wood siding, while being attractive, requires periodic painting, staining or finishing. Wood siding may also be susceptible to insect attack if not finished properly. This type of siding may also experience uneven weathering for unfinished surfaces, and has a tendency to split, cup, check or warp. Wood shingle siding has the additional problem of being relatively slow to install. In addition, clear wood products are slowly becoming more scarce and are becoming more expensive.
In an effort to avoid these problems, aluminum siding was developed, and has enjoyed a widespread acceptance nationwide. Aluminum siding is normally made by a roll forming process and is factory painted or enameled so as to require substantially no maintenance during the life of the installation. However, metal siding tends to be energy inefficient and may transfer substantial quantities of heat.
More recently, rigid plastic material has been used as a substitute for aluminum siding, with the most typical siding material being made of a vinyl polymer, e.g., polyvinyl chloride (PVC). Such plastic siding can be extruded in a continuous fashion or molded, after which lengths are cut to the desired length. Siding of this nature can be pigmented so as to be extruded or molded in the requisite color, thus avoiding the need for painting. However, it is difficult for the home owner to refinish this type of siding in a different color.
While aluminum and plastic sidings have obvious advantages, such as a preformed surface finish and the elimination of maintenance, these siding choices pose certain inherent disadvantages. First, aluminum and plastic siding can be damaged when struck by a hard object such as stones, hail, or even a ladder which is carelessly handled. Repairing such dents in aluminum and plastic siding is difficult. Conventional vinyl siding has an unattractive or unnatural softness or "give" to the touch," because extruded vinyl areas having less than about 0.100 of an inch in thickness are unduly flexible compared with the rigid look and feel of wood, stone, brick or stucco.
In addition, most plastic and metal sidings are subject to "canning," i.e., surface distortions from temperature differences and unequal stress on different parts of the siding. These temperature differences cause unsightly bulges and depressions at the visible surface of the siding. Vinyl siding has a high coefficient of thermal expansion and contraction. In order to accommodate this and to achieve the desired protective coverage, an installer will often substantially overlap the vertical edges of vinyl siding. This causes noticeable, unattractive, outward bends in the ends of the overlapping end portions of the siding.
Moreover, conventional plastic siding often presents a poor imitation of wood textures and unattractive butt joints. Extruded vinyl siding often has a synthetic-appearing graining which is rolled into the extruded product after a partially congealed (solidified) "skin" has formed on the extruded product. Such a synthetic-appearing graining repeats itself at frequent intervals along the length of the vinyl siding. This frequent repetition is caused by a relatively short circumference around the hardened-steel roller die on which the makes the graining pattern. Consumers do not value such vinyl siding highly.
Polymer materials have been combined with fibers to make extruded materials. Most commonly, polyvinyl chloride, polystyrene, and polyethylene thermoplastics have been used in such products. However, such materials have not successfully been used in the form of a siding member or any other type of structural member. Prior extruded thermoplastic composite materials cannot provide thermal and structural properties similar to wood or other structural materials. The prior extruded composite materials fail to have sufficient modulus, compressive strength, and coefficient of thermal expansion, all of which is necessary for an acceptable siding assembly. The structural characteristics of prior composite materials have not permitted any structural member to have a hollow profile design. Typical commodity plastics have achieved a modulus no greater than about 500,000 psi. In addition, prior attempts have often used a non-cellulosic fiber such as a glass or carbon fiber, which are more expensive than the preferred cellulosic fiber of the present invention.
Polyvinyl chloride has been combined with wood to make improved extruded materials. Such materials have successfully been used in the form of a structural member that is a direct replacement for wood. These extruded materials have sufficient modulus, compressive strength, coefficient of thermal expansion to match wood to produce a direct replacement material. Typical composite materials have achieved a modulus greater than about 500,000 and greater than 800,000 psi, an acceptable COTE, tensile strength, compressive strength, etc. Deaner et al., U.S. Pat. Nos. 5,406,768 and 5,441,801, U.S. Ser. Nos. 08/224,396, 08/224,399, 08/326,472, 08/326,479, 08/326,480, 08/372,101 and 08/326,481 disclose a PVC/wood fiber composite that can be used as a high strength material in a structural member. This PVC/fiber composite has utility in many window and door applications, as well as many other applications.
In addition, prior composites have not been durable enough to withstand the effects of weathering, which is an essential characteristic for siding. Further, many prior art extruded composites must be milled after extrusion to a final useful shape.
Accordingly, a substantial need exists for the development of a siding formed from a suitable composite material which can be directly formed by extrusion into reproducible, stable shapes advantageous for use as siding members. The siding structure must have resistance to weathering, relatively high strength and stiffness, an acceptable coefficient of thermal expansion, low thermal transmission, resistance to insect attack and rot, and a hardness and rigidity that permits sawing, milling, and fastening retention comparable to wood. The material must be easily formable and able to maintain reproducible stable dimensions, while having the ability to be cut, milled, drilled and fastened at least as well as wooden members.
A further need has existed for many years with respect to the byproduct streams produced during the conventional manufacture of wooden windows and doors. These byproduct streams have substantial quantities of wood trim pieces, sawdust, wood milling byproducts, recycled thermoplastics including recycled polyvinyl chloride, and other byproduct streams including waste adhesive, rubber seals, etc. Commonly, these materials are burned for their heat value and electrical power generation or are shipped to a landfill for disposal. Such byproduct streams are contaminated with hot melt and solvent-based adhesives, thermoplastic materials such as polyvinyl chloride, paint preservatives and other organic materials. A substantial need exists to find a productive, environmentally compatible use for such byproduct streams to avoid disposal of material in an environmentally harmful way.